The amount students fail to repay has been decreasing for years. It's currently down to 27p in the £1 because of the changes to the plans - higher repayments over longer - so it's not as simple as "well it doesn't matter as most don't repay". Most do repay.
Thank god they are increasing though. Universities are in a shit show due to the conservative government freezes with almost half reporting a deficit this year. It costs about £3K a year more per student to teach them than they pay for, this couldn't just go on. Not to mentioned falling international student numbers because of the anti-immigration rhetoric and the fact they count as migrants (nuts when most are temporary), higher costs including research costs, more reporting needed which costs more, and the fact that after 2030, the number of 18yos is going to fall putting income at risk.
I only wish they were rising more if we're going to have fees (whole other debate). £10.5K still means the fees are worth less than when they were introduced in 2012. Plus the average cost of a private primary education is over £15K now, are we really saying higher education is/should be cheaper to provide?